Film badge with improved radiation filtering structures

ABSTRACT

A radiation monitoring film pack and a holder therefor are disclosed. The film pack has a wrapper with a flap extending from it carrying identifying data. The holder defines a slot for receiving the film pack, novel U-shaped radiation filters for shielding the film from edgewise, as well as head-on radiation, and a frame which overlies the film-holding structure and holds the flap such that a surface on which the identifying data appears is visible.

United States Patent lnventor Eric T. Clarke Lexington, Mass.

Appl. No. 756,582

Filed Aug. 30, 1968 Patented Mar. 2, 1971 Assignee Technical Operations,Incorporated Burlington, Mass.

FILM BADGE WITH IMPROVED RADIATION FILTERING STRUCTURES 2 Claims, 10Drawing Figs.

Int. Cl G01t 1/08 Field of Search 250/ 8 3 [56] References Cited UNITEDSTATES PATENTS 2,496,218 l/l950 Kieffer 250/83ph 2,624,846 l/1953Tochilin et a1 250/83ph Primary ExaminerWalter Stolwein AssistantExaminerMorton J. Frome Attorneys-Alfred H. Rosen and John H. CoultABSTRACT: A radiation monitoring film pack and a holder therefor aredisclosed. The film pack has a wrapper with a flap extending from itcarrying identifying data. The holder defines a slot for receiving thefilm pack, novel U-shaped radiation filters for shielding the film fromedgewise, as well as head-on radiation, and a frame which overlies thefilm-holding structure and holds the flap such that a surface on whichthe identifying data appears is visible.

PATENTED MAR 2 Ian SHEET 2 OF 2 ERIC [CLARKE INVENTOR AL FRED H ROSEN0nd JOH/VH c0011 ATTORNEYS FELM BADGE WITH IMPROVED RADIATION FILTERINGSTRUCTURES CROSS-REFERENCE TO RELATED APPLICATIONS This applicationrelates to, but is in no way dependent upon, copending applications ofRobert J. Prest, Ser. No. 534,255 filed Jan. 4, 1966 now abandoned; andSer. No. 671,390, filed Sept. 28, 1967 now Pat. No. 3,567,933.

BACKGROUND OF THE INVENTION This invention, in general, relates toradiation-monitoring film badges worn by people who spend time in thevicinity of radioactivity such as ionizing radiation or lower energyradiation that is capable of producing secondary ionizing effects. Moreparticularly, it relates to film badges that are improved with respectto size, cost and adaptation to mass processing techniques. The specificcontribution of this invention concerns improved radiation shieldingstructures.

FIG. I is a full scale illustration of a typical prior art film badge.These badges are restricted in size and shape by the conventional use ofdental X-ray film packs. These film packs have been used due to theirready commercial availability. While the desirability of a differenttype of film pack for badge use has been obvious for some time, therehas been no system devised that would provide the desired advantagesparticularly without incurring intolerable costs in producing a new typeof pack.

The size of the conventional badge is a problem for people whosegreatest radiation exposure is at their hands, for example. A smallerbadge could be worn more readily as a finger ring or on a wrist strap. Avery small amount of the film is actually used for determining radiationexposure and the excess film is needed to enable identification markingon the film. This is done for example, using X-ray exposures through astencil or the like so as to penetrate the pack. The dental films alsorequire individual handling since they are not adapted for operation incontinuous webs with accurate position information. I

The above-referenced copending applications describe and claim filmbadges of reduced size using strips of film adapted for splicing intoreels for mass production processing. Sprocket apertures like those usedin moving picture film are provided on the strips for accurate positioninformation. Identification data is provided directly on the film stripswith a marking material that does not interfere with the utilization ofthe film. An extended free flap of the pack wrapper provides a surfacefor external identification data and coacts with a unique holder orbadge to provide readily visible identification without increasing theface area or reducing the effectiveness of the film.

These improved film badges, like all prior art badges, suffer from theinability to shield the film from radiation entering edgewise of thefilm.

OBJECTS OF THE INVENTION It is an object of this invention to provideimproved radiation filtering structures for film badges designed tomonitor high energy radiation. More specifically, it is an object toprovide structures for filtering radiation approaching the film edgewiseas well as head-on.

It is another object to provide radiation filters for film badges whichare easier to fabricate and incorporate into a film badge and whichrender the associated film badges less expensive to produce.

Further objects and advantages of the invention will in part be obviousand will in part become apparent as the following description proceeds.

The features of novelty which characterize the invention will be pointedout with particularity in the claims annexed to and forming a part ofthis specification.

BRIEF DESCRIPTION OF THE DRAWINGS For a fuller understanding of theinvention, reference may be had to the following detailed descriptiontaken in connection with the accompanying drawings, wherein:

FIG. 1 is a front elevation of a prior art film badge;

FIGS. 27 illustrate an improved film badge described and claimed in thefirst of the above-referenced copending applications;

FIG. 2 is a front elevation view of the said improved film badge;

FIG. 3 is an isometric projection view showing a film holder or badgeaccording to the referenced invention;

FIG. 4 is a view of a low sensitivity film strip;

FIG. 5 is a view of a high sensitivity film strip;

FIG. 6 is a fragmentary perspective view of a film pack according to thereferenced invention with one corner folded over to reveal otherwisehidden structure;

FIG. 7 is an enlarged cross section taken along line 7-7 of FIG. 2;

FIG. 8 illustrates another improved film badge described and claimed inpart in the second of the above-referenced applications;

FIG. 9 is a section view of the FIG. 8 badge illustrating novelradiation filtering structures implementing the teachings of thisinvention; and

FIG. 10 is a fragmentary exploded perspective view of the FIG. 8 badgeillustrating my novel radiation filters.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a showing of priorart already mentioned. It shows in full scale a typical prior art badge.For comparison purposes FIG. 2 shows an improved badge in accordancewith the above-referenced invention in a one-to-one'scale. The frontelevation of FIG. 2 shows a frame member 10 containing a window 11 forviewing identification data 12 on the face 13 of a portion of a filmpack supported in the frame. Measurements of F IGS. l and 2 will showthat the surface area of the badge in accordance with the invention isabout l/ s quare inches as compared to about 3%square inches of theprior art badge of FIG. 1.

An improved film holder in accordance with the abovereferenced inventionis illustrated in an opened-up condition in FIG. 3 and comprises a firstmember 15 rectangular in shape and having side edges 16 and 17 thereinrelatively long as compared to the ends 18. Member 15 is suitably madeof a rigid or semirigid material such as metal or certain plastics andcontains one or more metallic filters that permit an energy independentsystem. In one preferred embodiment, member 15 is made of aluminum andhas a first filter 20 of cadmium about one-fourth inch square and 1 mm.thick and a second filter 21 of copper about one-fourth inch square andone-fourth mm. thick. These dimensions are not critical to the inventionand are set forth only to provide a complete disclosure of a specificembodiment. The aluminum of member 15, which may be about one-sixteenthof an inch thick, shields against the softest X-rays and lower radiationenergy levels. The copper filter 21 shields against radiation belowabout 25 kilo-electron-volts energy. The cadmium filter 20 shieldsagainst substantially all radiation below about 50 kilo-electron-voltsenergy. The ends 18 of member 15 extend upward a small amount above theplane of member 15 providing support for a hinge connecting member 15 toa second member 22.

Second member 22 is rectangular in shape and similar to member 15 butsomewhat smaller in rectangular dimensions. One specific embodiment asillustrated in FIG. 3 uses a hinge made with pins extending throughholes 23 in ends 18 and extending into an enlarged edge 25 of member 22.This hinge secures one edge of member 22 along edge 17 of member 15.Member 22 contains a cadmium filter 26 and a copper filter 27substantially identical to filters 20 and 21, respectively, in member 15and arranged to register precisely with filters 20 and 21, respectively,when member 22 is folded across member 15. A window 28 is also suitablyprovided in member 22 for passing radiation having an energy below thepenetration level for the aluminum.

A third member is hinged to edge 16 of member and incorporates the frameshown in FIG. 2 around an open window 11. Member 10 suitably carriesspring metal clamping devices 3i so that when second member 22 is foldeddown across first member 15 and third member 10 is then folded acrosssecond member 22 clamping devices 31 are clamped onto edge 17 of firstmember 15 securing the assembly together (see FIG. 7). Third member 10can be made of materials such as stainless steel, brass, copper, orother metals plated or otherwise. It may also be made of various othermaterials, such as plastics materials, suited as a decorative frame withmeans to secure the assembly together. While the first and secondmembers 15 and 22 have been described as being made of aluminum, theycan also be made of other materials providing the shielding effect ofaluminum is supplied by other means, such as appropriate inserts, or awrapping in the film pack.

FIGS. 4 and 5 illustrate film strips 32 and 33, respectively, to beutilized in the present invention. In one embodiment these have beenmade identical to pieces of 16 mm. film sliced in half giving a width ofabout 8 mm. with sprocket apertures 35 along one edge for accuratepositioning in processing equipment. Each of the film strips isimprinted with identification data such as a serial number 36. Thisserial number is suitably typed, stamped, or printed on the film using amarking material. Marking materials commonly used in typewriter ribbonshave been found suitable. Pigments in waxy binder materials aregenerally operative. Printing of data on these strips in the suggestedway leaves a clear marking that is not necessarily indelible. However,as will be seen, the film strips are securely wrapped in a pack duringuse, and they can be handled automatically in processing equipment bothbefore and after use. Thus no problem is encountered with deteriorationor smearing of the markings. Film strips of FIG. 4 and 5 are illustratedas identical in size and shape; however, they are shown separately ashaving different respective sensitizations. Together their sensitivitiesare intended to cover ionizing radiation and beta particles. Ionizingradiation as used herein is to be taken as including radiation that iscapable of producing secondary ionizing effects. For example, the filmstrip in FIG. 4 may be highly sensitive so as to be capable of recordingexposures as small as one millirem. Rem will be recognized as roentgenequivalent man. The film strip of FIG. 5 has a much lower sensitivity,for example, it is appropriately sensitive so as to show densityvariations with doses up to as much as 300,000 millirems. In use in abadge the two film strips are placed in register one on top of theother.

FIG. 6 shows a wrapper made up of layers that are respectivelyreflective and absorptive of visible light. An interior layer 410 issuitably black cellulosic material while the exterior layer 41 may be awhite cellulosic material. In a preferred embodiment a thin metal foilsuch as .aluminum foil 42 is laminated between layers 40 and 41.

In making up the film pack at least one strip of film and preferably twostrips, as in FIGS. 4 and 5, are positioned against the interior layer40 of the wrapper and a portion of the wrapper 43 is folded over toenvelop the film strips as shown at the left side of FIG. 6. The surfaceof interior layer 40 is desirably coated with a fusible plastic coatingso that the edges of portion 43 may be heat sealed around film strips 32and 33 providing a tightly sealed enclosure for the film stripscompletely opaque to visible light. A second portion 45 of the wrapperextends out from the enveloping portion 43 to form anidentification-data member, as shown at the right side of FIG. 6 and canbe imprinted on the exterior layer 41 with identification data such asillustrated in FIG. 2. The wrapper enveloping the film strips is thenpositioned in the badge or holder of FIG. 3 as illustrated in thecross-sectional view of FIG. 7.

Cross section of FIG. 7 is enlarged for better illustration and is takenthrough line 7-7 of FIG. 2 Portion 43 of the film wrapper carrying filmstrips 32 and 33 is positioned on top of member 15 and member 22 isfolded up and over, completely covering portion 43. Extending flapportion 45 is then brought over on top of member 22 and is securedfirmly in place by crossing frame member 10 across it clamping theassembly together.

The badge assembly has been made with various means for attaching to aperson. These means (not shown) include a finger ring, a tie clip, snapsfor attaching to a laboratory smock or the like, and a wrist band.

In film badges as described above, substantially the entire viewablearea of the badge is available at window 11 for identifying information.The film strips which, as illustrated, can be as little as 8 millimeterswide, provide space along their entire lengths near a first edge foridentification data and space along their entire lengths near theopposite edge for position indexing means. Adequate space is stillavailable along the length of each strip between identification data andindexing means for radiation exposure measurements. However, it is to beunderstood that neither the markings for data nor the indexing meansneed be of a form that interferes with exposure or exposuremeasurements.

FIGS. 8-10 show an embodiment of the improved badge which incorporatesthe teachings of, my invention. This badge has members 102 and 104(corresponding to members 15 and 22, respectively, in FIG. 3)permanently fastened together. These members provide a slotlike opening106 between them for reception of the film-enveloping portion 43 of thefilm package (see FIG. 6). The identification-data member 45 can then beheld between the one of film-holding members 102 and an apertured thirdmember 108 (corresponding to the apertured frame member 10 in FIG. 3which is hinged to the other of the film-holding members 104 in themanner illustrated in FIG. 7. The plastic material of which this badgeis preferably made is an absorber of the radiation sought to bemonitored, and therefore takes part in the radiation monitoringfunction. A suitable plastic material is polypropylene, but this isexemplary only, since many suitable plastic materials are available. Thechoice of filters vary widely, depending upon the application. Oneexample is illustrated and described in detail in connection with FIG.3. In the FIGS. 8-10 embodiment one of the film-holding members 102 hasan aperture 110 and a portion 112 of reduced thickness in it for use inthe radiation monitoring function. These have been used in combinationwith metallic filters, to be described in detail hereinafter, asfollows:

a. a filter 1 14 of tin and lead combined;

b. a filter 116 of aluminum adjacent the portion 112 of reducedthickness;

c. a filter consisting of the full thickness plastic of both members 104and 102; and

d. a filter adjacent the aperture 110 consisting of the full thicknessof only member 102.

As suggested above, prior art film badges have all utilized radiationfilters comprising one or a pair of individual filter elements disposedadjacent the radiation sensitive film. Such an arrangement allowsradiation actinic to the film to enter beneath the edges of the filterelements without attenuation attenuation thereby, and to expose thefilm. Erroneous dosage readings are very apt to result from this leakageof radiation to the film. In accordance with this invention, improvedradiation filtering structures are provided which effectively preventexposure of the film beneath the filter except by filtered radiation. Bythis invention, erroneous radiation measurements caused by the describededgewise entrance of radiation beneath the filter elements is precluded.

To this end, filters 114 and 116 are formed from a single strip ofshielding material folded upon itself in a Ll-shaped configuration. Thefilters 114, 116 are ensconced in pockets molded in the support members102, 104 with the slot formed within the filters being registered withthe slotlike opening I06 defined by the support members 102, 104. Thus,with a film packet disposed in the slot, the filters effectively wraparound the lowermost edge of the film and prevent the impingement ofunattenuated radiation on the radiation-sensitive film within thepacket.

in addition to the above, filters fabricated according to this inventionare easier to fabricate and to incorporate into the film badges, duelargely to their integral construction, and are effective to lower thecost of film badge manufacture.

The invention is not limited to the particular details of constructionof the embodiments depicted, and it is contemplated that various andother modifications and applications will occur to those skilled in theart.

Therefore, because certain changes may be made in the above-describedproduct without departing from the true spirit and scope of theinvention herein involved, it is intended that the subject matter of theabove depiction shall be interpreted as illustrative and not in alimiting sense.

lclaim:

1. A film badge useful for monitoring high energy radiation comprising:

a radiation-sensitive film element;

a film packet opaque to visible light comprising a portion completelyenveloping said element and a flexible flap extending from said portionwith a surface for identification data;

a holder defining a slot for receiving said portion of said packetenveloping said element;

a radiation filter for attenuating radiation before impingement uponsaid film elemenfisaid filter comprising a U- shaped radiation shieldingmember supported in said holder in registration with said slot forreceiving said portion of a film packet inserted into'said slot; and

clamping means pivotally connected to said holder, said clamping meansbeing movable between an open position for loading said film packet anda closed portion against said holder wherein said clamping means acts tobend said packet such that said flap is clamped against said holder,said clamping means defining an aperture through which saididentification data on said flap is visible when said flap is in itsclamped position.

2. The badge defined by claim 1 wherein said holder comprises two matingelements adapted to capture said radiation filter therebetween.

1. A film badge useful for monitoring high energy radiation comprising:a radiation-sensitive film element; a film packet opaque to visiblelight comprising a portion completely enveloping said element and aflexible flap extending from said portion with a surface foridentification data; a holder defining a slot for receiving said portionof said packet enveloping said element; a radiation filter forattenuating radiation before impingement upon said film element, saidfilter comprising a U-shaped radiation shielding member supported insaid holder in registration with said slot for receiving said portion ofa film packet inserted into said slot; and clamping means pivotallyconnected to said holder, said clamping means being movable between anopen position for loading said film packet and a closed portion againstsaid holder wherein said clamping means acts to bend said packet suchthat said flap is clamped against said holder, said clamping meansdefining an aperture through which said identification data on said flapis visible when said flap is in its clamped position.
 2. The badgedefined by claim 1 wherein said holder comprises two mating elementsadapted to capture said radiation filter therebetween.